How Often Should You Clean Solar Panels in the UK?
Updated: May 2026 · By Depth of Light Ltd, Milton Keynes
Short answer: once or twice a year for most UK homes. Properties near trees, farmland or busy roads benefit from twice yearly. Here's the detail.
Maximum output loss from heavily soiled panels. On a 4 kWp system in Milton Keynes that's £100-£300 of generation per year — far more than a clean costs.
Why cleaning matters
UK solar panels collect dust, pollen, bird droppings, lichen and the residue of every wet/dry cycle. Lightly soiled panels lose 5-10% of output. Heavily soiled panels can lose up to 25%. On a 4 kWp system that's £100-£300 of generation per year — far more than a clean costs.
The "rain will clean them" myth
Rain helps with light dust but does nothing for stubborn deposits — bird droppings dry on, pollen forms a sticky film, and lichen actively grows. After a year of UK weather, most panels need a proper clean to restore peak output.
How often, by location
| Property type | Recommended cleaning |
|---|---|
| Standard suburban | Once a year |
| Near mature trees | Twice a year (spring + autumn) |
| Near farmland or open countryside | Twice a year |
| Near busy road or industrial | Twice a year |
| Coastal (salt deposits) | Twice a year |
| Near construction site (temporary) | Monthly until complete |
How to clean them properly
The right method is a pure water fed pole system from ground level. Why:
- No detergents — these leave streaks and can damage anti-reflective coatings
- No ladders on the panels — risk of damage and personal injury
- No dry brushing — micro-scratches the glass over time
- No high-pressure jets — can force water under panel seals and damage cells
What does it cost in 2026?
- Up to 10 panels: from £80
- 11-16 panels: from £110
- 17+ panels: from £140 (quoted per site)
Bundle it with an annual health check
The most cost-effective way to look after solar is an annual maintenance plan combining one cleaning + one full health check at a reduced bundled rate. From £140/year for a typical 4 kWp system. We send a reminder so you don't have to think about it.
Will cleaning void my warranty?
No — done correctly. Pure water fed pole cleaning is the manufacturer-recommended method. We're MCS certified, which is what most warranties require. Book a clean.
Book a Solar Clean
Free survey across Milton Keynes and Buckinghamshire — MCS & NAPIT certified.